In an office building, 42 offices are currently being rented.
This represents 40% of the total units.
Let x be the total number of offices.
Then we can write
[tex]\begin{gathered} 40\%\; of\; x=42 \\ \frac{40}{100}\cdot x=42 \\ 0.40\cdot x=42 \\ x=\frac{42}{0.40} \\ x=105 \end{gathered}[/tex]Therefore, there are 105 offices in the building.
